JP2001124058A - Brushless motor with dynamic pressure fluid bearing of heat radiation type - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brushless motor furnished with dynamic pressure fluid bearing of high performance and high-speed operation capable of promoting the heat radiation and involving less thermal influence. SOLUTION: The brushless motor with dynamic pressure fluid bearing is structured so that radiation fins are installed on a rotor yoke and hole(s) is provided in a circuit board for releasing the heat from inside the rotor so that the heat radiating efficiency of the bearing surface is improved forcedly, and also temperature rise of the bearing surface is suppressed and heat emission from the internal oil is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention P. The present invention relates to a structure of a hydrodynamic fluid bearing brushless motor used for OA equipment such as a printer and a printer.

[0002]

2. Description of the Related Art In recent years, P.I. P. OA devices such as C tend to have high functions, high accuracy, and high speed in response to user needs, and low-cost products are demanded. Under such market trends, high-performance, high-precision, high-speed, and inexpensive products are also demanded for a hydrodynamic fluid bearing brushless motor used to drive the functions of various parts of OA equipment and the like. ing.

As shown in FIG. 1, in a brushless motor of a hydrodynamic bearing, a magnetic field is generated by an electromagnetic action in a core 5 provided with a winding. Repulsion and attraction work between this magnetic field and the magnetic field of the magnet 9 disposed opposite the core 5, and the rotor yoke 3 holding the magnet rotates integrally with the rotating shaft 1.

The rotating shaft 1 has a hydrodynamic bearing (sleeve) so as to cover the rotating shaft 1 in the axial direction.
The rotating shaft 1 integrated with the rotor yoke 3 is held by dynamic pressure generated during rotation by the hydrodynamic bearing, the rotating shaft 1 and the lubricating fluid interposed therebetween. During the rotation, the holding force (dynamic pressure) increases as the number of rotations increases. Also,
Increasing the number of revolutions with an increase in speed requires increasing the holding force. Heat is generated inside the hydrodynamic bearing,
This leads to an increase in the temperature of the interposed lubricating fluid. With this, the temperature rise of each component existing inside the rotor is also led, and the characteristics of the brushless motor of the hydrodynamic bearing are reduced.

[0005]

The holding force generates heat inside the hydrodynamic bearing due to the shearing force of the oil due to the rotation and the frictional force due to the viscosity of the oil, leading to an increase in the temperature of the interposed oil. Along with this, a decrease in holding force and an increase in the temperature of each component existing inside the rotor due to an increase in the temperature of the hydrodynamic bearing itself also lead to a reduction in motor characteristics of the hydrodynamic fluid bearing brushless motor.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a high-performance, high-speed fluid dynamic bearing brushless motor that promotes heat radiation and is less affected by temperature.

[0007]

A heat radiation fin is provided on a rotor yoke, and a hole is formed in a circuit board to remove heat inside the rotor and forcibly improve the heat radiation efficiency of the surface of the hydrodynamic bearing. The temperature rise on the surface can be suppressed, and the heat generation of the internal oil can be suppressed. Create a flow of air from the rotor to the board through the holes in the circuit board.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One of the heat sources of a hydrodynamic fluid bearing brushless motor
The lubricating fluid for generating dynamic pressure in the bearing of the hydrodynamic bearing (sleeve) 7 is provided on the radiating fins 2 formed on the upper surface of the sheet metal rotor yoke 3 by press working and on the fin portions. The air heated to the outside of the motor is removed by the holes 10.

The heat generated in the dynamic pressure generating groove 6 and the temperature rise on the surface of the dynamic pressure fluid bearing 7 are guided to the outside by radiating fins to suppress the temperature rise on the surface of the dynamic pressure fluid bearing 7 and Suppress heat generation of the interposed lubricating fluid.

The heated gas from the surface of the hydrodynamic bearing 7 is
Holes 8 provided in the circuit board 4 near the mounting of the hydrodynamic bearing
Outside air is taken into the motor, and the flow path is secured. The shape of the radiation fin 2 is such that a vertical surface is provided on the upper surface of the sheet metal rotor yoke 3 at an angle of 45 degrees with respect to the center of the rotor,
A hole 10 for taking in outside air is arranged on the surface. From the upper part of the vertical plane to the next vertical plane, the blades are formed in the same direction as the rotation direction, the upper part of the vertical plane is horizontal, and the next vertical plane has an angle of 45 degrees from the circle inside the fin forming part They are connected by an appropriate R-plane shape. .

[0011]

The heat radiation fins and the holes provided in the fin portions remove the inside air at a higher temperature than the inside of the motor, thereby increasing the surface of the hydrodynamic bearing (sleeve) and the lubricating fluid for generating the dynamic pressure. It is possible to suppress the temperature, and it is possible to suppress the deterioration of the lubricating fluid due to the temperature rise and the accompanying decrease in motor characteristics.

Since the radiation fin is formed integrally with the rotor, which is a rotating body, the efficiency of suppressing the temperature rise is proportional to the number of rotations. In addition, since the heat radiation fins are formed simultaneously by pressing when the rotor yoke is formed, the number of components does not increase, so that the functions can be increased at low cost.

[Brief description of the drawings]

FIG. 1 is a sectional view of a brushless motor for radiating dynamic pressure bearing according to an embodiment of the present invention.

FIG. 2 is a sectional view, a plan view, and a perspective view of a rotor yoke according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotating shaft 2 Radiation fin 3 Rotor yoke 4 Circuit board 5 Core 6 Dynamic pressure generation groove 7 Dynamic pressure fluid bearing (sleeve) 8 Hole 9 Magnet 10 Hole

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H02K 21/22 H02K 21/22 M (72) Inventor Hiromasa Masuda 2-4-19 Nakane, Meguro-ku, Tokyo Canon Seiki Co., Ltd. In-company F-term (reference) 3J011 AA04 AA09 BA02 BA04 BA10 CA02 3J017 EA03 GA03 5H607 AA02 BB01 BB09 CC01 GG01 GG03 GG12 GG15 5H609 BB03 BB15 BB18 PP02 PP11 QQ02 QQ12 QQ23 RR06 RR07 RR17 RR17 RR17 RR17 RR17 RR17 RR17 RR17 RR17 RR17 RR17 RR17 HH01 JK07 JK08 JK11 JK14 JK19

Claims (4)

[Claims] A magnet, a rotor yoke and a shaft rotate integrally, and the rotating shaft has a hydrodynamic bearing so as to cover the rotating shaft in the axial direction, and the hydrodynamic bearing, the rotating shaft and lubrication interposed therebetween. A dynamic pressure fluid bearing brushless motor in which the rotating shaft is held by the dynamic pressure generated during rotation with the fluid, by providing heat radiation fins on the upper surface of the rotor yoke in the same direction as the rotation direction, and by installing holes in the rotating substrate A brushless motor for radiating hydrodynamic bearing, characterized in that, when the rotor rotates, the radiating hydrodynamic bearing surface and the lubricating fluid in the hydrodynamic bearing surface promote heat radiation and suppress temperature rise. 2. A sleeve having a bearing surface therein, a core disposed radially outward of the sleeve, a rotating shaft rotatably bearing on the bearing surface of the sleeve, and a rotor yoke attached to the rotating shaft. A rotor comprising a magnet attached to the rotor yoke so as to generate an electromagnetic force together with the core; a dynamic pressure generating groove formed on either a bearing surface of the sleeve or an outer peripheral surface of the rotating shaft; A radiating fin formed on the rotor yoke configured to discharge air from inside the rotor yoke where the sleeve is present to outside the rotor yoke when the rotor rotates, characterized in that: Bearing brushless motor. 3. The brushless motor according to claim 2, wherein said rotor yoke is a ring-shaped plate portion fixed horizontally to said rotary shaft and a cylinder vertically suspended from an outer peripheral edge of said plate portion. The heat radiation fin is formed at the center of the plate portion, the sleeve is supported on a circuit board, and the circuit board is provided with a rotor yoke for discharging air discharged outside the rotor yoke by the heat radiation fin. A heat-dissipating hydrodynamic bearing brushless motor, characterized in that a hole to be introduced therein is formed. 4. The brushless motor according to claim 1, wherein said radiating fin has a plurality of holes formed to discharge air when the rotor rotates. And a plurality of blades arranged obliquely so as to direct air discharged through the holes from the inside of the rotor yoke to the outside of the rotor yoke.